The goal of this project is to develop a registry of research subjects with OP, with a risk of developing OP, and healthy controls. DXA scans will be performed on willing individuals at the spine, hips, and forearms and possibly the legs and heels in order to determine BMD. Subjects will also be asked to provide two (10 ml) blood samples, which may be used to analyze Vitamin D levels and/or other bone markers. By participating in the registry, subjects will be considered for current and future clinical research studies.